Grassland Grouse and Their Conservation by Paul A. Johnsgard

Author:Paul A. Johnsgard [Johnsgard, Paul A.]
Language: eng
Format: epub
ISBN: 978-1-935623-67-0
Publisher: Smithsonian
Published: 2014-12-03T00:00:00+00:00

TERRITORIAL AND COURTSHIP DISPLAYS

Each male spends most of the time in his own territory performing a variety of postures, movements, and calls that serve to ward off potential competitors and to attract females. The adult males (Figure 9), as well as their display behaviors, are virtually identical to those of Attwater’s prairie-chicken, and so far as is known, the heath hen. The most characteristic of all greater prairie-chickens’ displays is the booming posture and call (Figure 10). It is essentially identical in the interior and Attwater’s races, and judging from available descriptions was probably identical in the extinct heath hen (compare Figures 2 and 10). In the heath hen it was called “tooting” by Alfred Gross, a term Ingemar Hjorth believed better fit the male’s associated vocalization and its associated foot-stamping sounds. He used that term to describe the call proper, whereas he called the postural component the “forward” display.

In assuming the forward posture, the bird’s tail is cocked to at least the vertical, the earlike feathers, called pinnae, are variably raised, and the primaries of both wings are lowered while still held within the flank feathers, rather than being spread laterally as in sharp-tailed grouse. The display sequence begins with a rapid foot-stamping that lasts up to two seconds, while the feet are alternately stamped at a rate of about 20 times per second, producing a sound audible up to 100 feet away. The tail is then quickly opened and shut twice, producing a single click audible only at close range, and the first of the three booming or tooting notes are uttered as the yellow air sacs rapidly inflate. The three-noted call varies little in loudness or in fundamental sound frequency, but the third and longest note (lasting about a second) has better developed harmonics, making its average pitch seem somewhat higher. The head is jerked down slightly during the first note, but not nearly so conspicuously as in the lesser prairie-chicken. The air sacs also vary slightly in degree of inflation during the three notes, being most highly expanded during the final note. The call’s typical transcription, “Old-Mul-dooon,” describes the sound well, a noise much like that produced by blowing over the opening of a large bottle. The tail is progressively spread and again closed toward the end of the vocalization, and the beak finally opens as the air sacs deflate. No special direction is maintained during booming; over time the male is likely to face all directions. Booming is performed by each male at a usual rate of several times per minute, but is especially frequent and intense when females make their appearance on the lek.

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